ART adherence and secondary prevention of HIV Anti-retroviral medications (ART) prevent the progression of HIV. However, substantial proportions of HIV positive individuals fail to adhere adequately to ART, resulting in spread of potentially drug-resistant strains to the community. A low cost method to boost ART adherence and thereby reduce the spread of HIV involves cell phone reminders, and our preliminary study (Hardy et al., 2011) finds significant effects of cell phone reminders for improving adherence. Contingency management (CM) also shows promise for improving ART adherence. CM involves providing tangible reinforcement each time the behavior (medication ingestion) is exhibited. Studies evaluating CM for increasing ART adherence have relied upon MEMS caps, but reinforcement of adherence via MEMS caps is done relatively infrequently and with delay, hindering its efficacy. Cell phones allow for reinforcement of adherence in real time. Because effect sizes of CM interventions are larger the more immediately the reinforcement is paired with the behavior targeted for change, integration of cell phone based reinforcement should improve adherence beyond reminders alone. Pilot data show feasibility, acceptability, and initial efficacy of cell phone administered CM using videoing recording techniques to verify medication adherence. Moreover, effective CM interventions have been shown to reduce risk behaviors in high-risk populations. In this study, we propose to randomize 165 HIV-positive patients to one of three 16-week treatment conditions: (1) standard care; (2) standard care + cell phone-based adherence reminders; or (3) standard care + cell phone-based adherence reminders and CM. In this latter condition, patients will earn reinforcement for sending in time- and date-stamped self videos of ART ingestion. Primary outcomes will include self-report measures of adherence and objective indices of viral loads, and effects will be evaluated both during the treatment period and throughout a one-year follow-up. Effects of these interventions on risk behaviors will be evaluated as well. We hypothesize that the cell phone reminder condition will improve adherence relative to standard care, and the cell phone reminder plus CM condition will have the best outcomes. We will also estimate the cost-effectiveness of these interventions. Results from this study may have widespread implications for the use of cell phones as a novel technology to improve initial adherence to ART, thereby reducing the spread of drug resistant HIV strains to the community.